Retractable antennas are well known and commonly used, particularly for radios in automobiles where it is advantageous to have the antenna unexposed to damage, vandalism, theft, and the like when the radio is not in use. Retraction of the antenna for a transmitting/receiving device such as the automobile radio reduces the opportunity for vandalism when the automobile is unattended, and for damage such as that possible as the automobile passes through an automatic car-wash. The growth in sales of such retractable antennas despite their additional initial cost to the consumer prove the value of such a feature to the marketplace.
The shafts of those antennas made to date are basically long thin cylindrical shafts which are either solid rods, hollow tubes, or a series of incrementally sized hollow tubes configured to form a telescoping tube assembly. Those antennas are retracted and extended through displacement along the axis of the cylindrical shaft by any one of a variety of motor driven or hydraulic methods which generally move the shaft through a flanged guide bushing that is fixed to a mounting surface such as the automobile fender.
The recent increases in the use and sales of cellular telephones for automobiles present a similar need to the consumer for a retractable cellular telephone antennas, yet those antenna used for the transmission/reception of cellular radiowaves employ a shaft whose shape is helical and therefore not well adapted for the axial displacement used for the common cylindrical antennas.